There is considerable interest in the development of alternative sources of fuels and chemicals, other than from petroleum resources. As the public discussion concerning the availability of petroleum resources and the need for alternative sources continues, it is anticipated that government mandates will expand the requirements for transportation fuels to include, at least in part, hydrocarbons derived from sources other than petroleum. As such, there is a need to develop alternative sources for hydrocarbons useful for producing fuels and chemicals.
One possible alternative source of hydrocarbons for producing fuels and chemicals is the natural carbon found in plants and animals. These so-called “natural” carbon resources (or renewable hydrocarbons) are widely available, and remain a target alternative source for the production of hydrocarbons. For example, it is known that carbohydrates and other sugar-based feedstocks can be used to produce ethanol, which has been blended with gasoline to provide an oxygenate to reduce emissions of uncombusted hydrocarbons. However, without government mandates, ethanol blending would diminish as it is not economically or energy efficient.
Carbohydrates, however, also can be used to produce fuel range hydrocarbons. The upgrading of biologically derived materials to materials useful in producing fuels is known in the art. However, many carbohydrates (e.g., starch) are undesirable as feed stocks due to the costs associated with converting them to a usable form. In addition, many carbohydrates are known to be “difficult” to convert due to their chemical structure, or that the hydrocarbon product produced is undesirable or will result in low quantities of desirable product. Among the compounds that are difficult to convert include compounds with low effective hydrogen to carbon ratios, including carbohydrates such as starches and sugars, carboxylic acids and anhydrides, lower glycols, glycerin and other polyols and short chain aldehydes. As such, efforts have been made to increase the effective hydrogen to carbon ratio of the materials including converting oxygenates in the presence of hydrogen, CO, steam, nitrogen, or other reactants, and by employing various catalysts. However, these processes are often complex and are costly, and the reaction products produced as a result of these processes are oftentimes undesirable or produce low weight percentage products, and often result in an increase in undesirable byproducts such as the production of carbon monoxide and carbon dioxide.
As such, development of a process for converting carbohydrates to hydrocarbons which yields significant quantities of desirable hydrocarbon products would be a significant contribution to the art. Furthermore, development of a conversion process for converting biological carbon to a hydrocarbon fuel or chemical product with reduced byproducts such as carbon monoxide and carbon dioxide, and reduced coke production, would be highly desirable.